Fix build/agent dependencies

Update the build/agent/install-deps configuration:
* correctly work on trusty+
* handle the extra dependencies that were in vagrant/bootstrap.sh
* specify minimum dependencies of icu-config
** precise-saucy: libicu-dev
** trusty+: icu-devtools

Change-Id: Ic294ab825c8aec9cb54c93454b4cf97750b2f5e9
Allow build-source-package.sh configurable

Allow the dependencies that are built (libpalaso/chorus) to be built
as either Debug or Release.  For some releases (e.g. alpha), we want
these dependencies built for debug.

Change-Id: I737eaa0fe546eb705c37bae16ea4aaac81a0871e
Improvements to Gecko Unit Tests

Some tests are failing in team city that don't
fail on other systems.  These changes improve
the way that failures are reported, showing the
actual values that were obtained in the test
run.

Change-Id: Ia375b19a68115c0069c6419b42909a962007dce3